The present invention relates to a method for operating a heating and cooling machine that functions on the basis of a regenerative gas cyclic process, as well as a heating and cooling machine for carrying out the method.
German Patent no: 195 16 499 describes, a method for a heating and cooling machine in which the combustion air needed for the source of the thermal driving energy is preheated by exhaust gases arising from combustion. The preheating of the combustion air increases the overall efficiency of the burner and the overall performance number of the heating and cooling machine; at the same time, the heating and cooling machine is configured such that for a predetermined size, only a predetermined maximum heat output can be achieved at an optimal performance number.
In order to meet an increased heat demand, it is conventional for example, in addition to operating a heat pump, to employ, in a parallel bivalent operating mode, a second heat producer, e.g., a conventional gas heat thermal element or electrical heating element.
The control process according to the present invention and the device for carrying out the control process have the advantage that the size of a heating and cooling machine required for a predetermined heat output can be maintained while the output or overall capacity of the heating and cooling machine is increased in an advantageous manner.
In the rare cases of extremely low external temperatures, and an associated higher heat energy demand, IT is possible, for example, to make available a required output of 20 kW by a heating and cooling machine that is designed for 15 kW, due to the fact that the preheating of the combustion air is dispensed with partially or totally, whereas the burner output is increased and the hot exhaust gas mass flow is conveyed to an exhaust-gas-water heat-exchanger for further heat energy utilization.
The data on the frequency distribution of the external temperature and the associated heat demand underlying a German standard (DIN 4702/8) show that a less than 80% utilization of a heat producer is sufficient to cover 96% of the annual cumulated heat delivery. For the remaining uncovered 4% heat demand, the control process according to the present invention can be applied in the form of an integrated bivalence.
The preheating of the combustion air is controlled in an advantageous manner by a bypass channel circumventing the exhaust-gas heat-exchanger.
In order to achieve continuous control of the combustion air preheating in accordance with the required heat output, it is proposed to control the bypass channel by a bypass valve.
The burner output is increased in an advantageous manner through the fact that the combustion air flow generated by a blower fan and the combustion gas quantity are increased while the air number is kept the same.